Climate change impacts, ranking severity

These are summer days and the blogging is slow. In the spirit of audience participation, here is a quick poll.

Which three of the following climate change impacts do you expect to be the most severe? Please answer first for 2050 and again for 2100. You can interpret ‘severity’ however you like: economic cost, number of deaths, total damage to ecosystems, etc.

Sea level rise

Droughts and floods

Extreme weather events

Ocean acidification

Ecosystem changes (such as invasive species)

Effects on pathogens (such as malaria)

Agricultural impacts

Impacts on fresh water quantity and quality

Other (please specify)

Clearly, there is some overlap between the options. There are also second-order effects to be considered, like the impact of agricultural changes on inter- and intra-state conflict.

2050: 8, 7, 6, plus ‘other’ referring to second order changes in human activity which contribute to deforestation (eg. palm oil instead of rainforest).
2100: basically the same again, with a query on 1.
A geographer I talked to a while back said that ‘back of the envelope’ calculations by leading glaciologists suggested Greenland would take a very, very long time to melt (certainly over 100 years) so huge sea level rises would be a long way in the future if they happened at all.

A geographer I talked to a while back said that ‘back of the envelope’ calculations by leading glaciologists suggested Greenland would take a very, very long time to melt (certainly over 100 years) so huge sea level rises would be a long way in the future if they happened at all.

People said the same thing about the Arctic icecap.

Supercomputer models are not up to the task of determining how the climatic system will change in response to radiative forcing changes. That is especially true in relation to feedback effects (like how loss of reflective ice begets further heating). I take no comfort from ‘back of the envelope’ calculations.

Sure, the ‘conventional wisdom’ of academia can be wrong & is always changing with new evidence. Reputedly, the glaciologists’ point was that even if we assumed that glaciers in Greenland would start to move as fast as any glaciers are known to have done (much, much faster than Greenland glaciers in the past) then the place is so vast that it would take a very long time for all that ice to reach the coast. That seems rather different to the Arctic where the ice was always floating on the sea.

It wouldn’t take the complete melting of Greenland to produce devastating consequences. Losing the whole ice sheet would incease sea levels by seven metres. A rise of just a metre or two would have a huge effect on many cities and agricultural areas.

Also, ice melting is not the only source of sea level rise. As the ocean warms, it also expands. The contribution of just thermal expansion might approach one metre by 2100.

I gotta say that my laywoman’s understanding of the IPCC models on sea level rise is that it conforms to my earlier claim “huge sea level rises would be a long way in the future if they happened at all”. That’s not to say that we shouldn’t worry about it, just that it doesn’t make my top 3.
So saying, I wouldn’t rush to buy a house on low lying coastline or floodplain.

According to the IPCC report—whose wording was agreed to by every member government, including the Saudis, the Chinese and the Bush administration—the earth is on an emissions path headed towards more than 5°C warming from pre-industrial levels this century.2 With such warming, the world faces multiple miseries, including:

* Sea level rise of 80 feet to 250 feet at a rate of six inches per decade (or more).
* Desertification of one third the planet and drought over half the planet, plus the loss of all inland glaciers.
* More than 70% of all species going extinct, plus extreme ocean acidification.

“UNTIL the 1970s Basra’s climate was like southern Europe’s,” recalls Shukri al-Hassan, an ecology professor in the Iraqi port city. Basra, he remembers, had so many canals that Iraqis dubbed it the Venice of the Middle East. Its Shatt al-Arab river watered copious marshlands, and in the 1970s irrigated some 10m palm trees, whose dates were considered the world’s finest. But war, salty water seeping in from the sea because of dams, and oil exploration which has pushed farmers off their land, have taken their toll. Most of the wetlands and orchards are now desert. Iraq now averages a sand or dust-storm once every three days. Last month Basra’s temperature reached 53.9ºC (129°F), a record beaten, fractionally, only by Kuwait and California’s Death Valley—and the latter figure is disputed.